Recently, as the resolution of a solid state imaging element such as a charge coupled device (CCD) image sensor, and a complementary metal oxide semiconductor (CMOS) image sensor becomes higher, a demand for an information device having an imaging function such as a digital still camera, a digital video camera, a cellular phone, and a personal digital assistant (PDA) is rapidly increasing. The information device having an imaging function as described above is referred to as an imaging apparatus.
A focusing control method which detects a distance to a main subject to focus on the subject include a contrast auto focus (AF) method and a phase difference AF method. Since the phase difference AF method may detect a focusing position with a high precision at a high speed as compared with the contrast AF method, the phase difference AF method is widely employed in various imaging apparatuses (see, e.g., Patent Literature 1).
Patent Literature 1 discloses an imaging element in which some of R pixel cells which detect a red light component, some of G pixel cells which detect a green light component, and some of B pixel cells which detect a blue light are used as focus detecting pixel cells of a photographing optical system.